Good point. Diplomacy always takes 1/10th of your account, rounded down. You probably wouldn't want to be handing out 90000 gold to everyone you see. Maybe increments of 10k?
Its not the only way. You simply don't have "Show Hidden Folders, files and drives" on.
Can't remember how to find the option on XP, but on Vista/W7 it should be "Open Explorer -> Organize (upper left corner) -> Folder and Search Options -> View (Tab) and then under advanced settings it should have the option to show hidden folders, files and drives.
After that then appdata should appear under the Users\Yourname\ folder.